A lot of research work is in progress to investigate, and find applications (e.g., super low threshold laser and quantum entanglement) for the peculiar physical properties of quantum dots (especially, semiconductor quantum dots) as a typical example of nanosized structures.
Typically, quantum dots are produced by (1) self-assembly into particles in chemical reaction or (2) MBE. The latter is a method of growing an extremely thin crystal film (equivalent to a thickness of a few atoms) on a wafer of a different semiconductor, such as silicon.
It is expected that the quantum dot will find applications in wide ranges of fields from computer-related fields to biotechnology. To use quantum dots in these fields, preferably, they have uniform diameters. Challenges for the applications include the development of technology that controls quantum dot size and arrangement.
A known technology that can control the size and arrangement of generated quantum dots is (3) a combination of MBE and a probe microscope for those quantum dots produced by one of the methods (Fujitsu Corp.; see “Proceeding of International Conference on the Physics of Semiconductors 2002”).
However, with this conventional technology, it is difficult to manipulate a large number of generated quantum dots efficiently.
Specifically, methods (1) and (2) are hardly capable of controlling the variations in the diameter of a large number of generated quantum dots to a value on the order of a few percent or less which is required for optical applications of quantum dots.
In method (3), MBE is used in combination with a probe microscope. An advantage of the method is that nanometer-sized quantum dots can be directly produced by manipulating the probe. Each probe can however manipulate only one dot. No more than a few probes can be used at a time. The fastest probe microscope normally takes about 0.1 seconds to make a single scan. Assuming, as an example, a process time of 0.1 seconds for each dot and the simultaneous use of 10 probes, about 100 dots can be processed in one second. This translates into the need for a fairly extended period of time if one wants to control variations in diameter of numerous quantum dots with method (3). The process efficiency is low.
The present invention, conceived in view of these issues, has an objective to provide a semiconductor quantum dot manipulating method and production/manipulation apparatus capable of controlling the size of a large number of generated semiconductor quantum dots to a value on the order of a few percent or less which is required for optical applications of the dots.